Speak, and I'll tell you who you are! By definition, a voice is a whole of sounds, produced by the vibrations of our vocal folds of course, by also by many other complex mechanisms. A voice can be transformed, and evolves with us during our life. Like a musical instrument, it allows us not only to communicate, but also to be recongnized and identified. Some people suffer from having a voice which is unappropriate to the physical appearance, but fortunately this kind of problems can be solved. What about nice and gentle voices ? Are they always linked to nice and gentles physical appearences ? And vice versa ? Matiere Grise finds out in its scientific investigation.